Choose from these words to fill the blanks below:

turtle, mud, appearance, pigment, Tyrannosaurus, velociraptor, toes, melanosomes, chemistry, Ankylosaurus, black, gila, scaly, fleshed, seldom, soft, scales, brown, ancestors, skin, sediment, bacteria, dermis, green, mummified, decomposes, spikes, fingernails, Cretaceous, feet, calcium, skin, adaptations, integumentary, volcanic, Wyoming, plates, corona, bristles, quickly, slowly, eumelanosomes, Theropods

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museums often display fully               fleshed-out models of dinosaurs

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paleontologists have some methods to determine the                     appearance of some dinosaurs based on dry bone fossils

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bones are hard, mineralized structures that rot away             slowly

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muscles, organs and skin decay               quickly

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they are             seldom fossilized

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however, sometimes paleontologists get a rare glimpse of a dinosaur's         soft anatomy

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footprint are natural molds of dinosaur         feet

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usually are no more than the sloppy outline of a dinosaur's         toes

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sometimes the tracks are so well preserved that they include impressions of the             scales from the sole of a dinosaur's foot

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in very rare cases dinosaurs were buried by       mud soon after death

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skin impressions formed in the mud before the flesh had time to rot away

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sometimes true fossils of the         skin, not just molds, can form

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these are referred to as                   mummified

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large regions of the skin hanging off the bones

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              Wyoming, 1910

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Hadrosaurs

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claws, beaks, hairs and feathers are composed of keratin

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harder than flesh and                     decomposes faster than bone

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rarely fossilizing

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                          integumentary structures, i.e. the organ system that protects the body from damage

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Psittacosaurus

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fossilized remains of tall                 bristles along of tails

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unclear what the bristles were for

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many dinosaur bones were discovered with fossilized feathers

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                        velociraptor has feathers

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many dinosaur groups, not just birds, had feathers

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bird fossils from early                     Cretaceous Period in China

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claws of hand on wing

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discoloration of the claw, where fingernail was

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shows feathers around body

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lake bed deposits

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                volcanic ash mixing in with silt

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like mud it preserves detail

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also alters the                   chemistry of the water

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so where features such as feathers and                       fingernails would normally be destroyed by decomposition by bacteria, this                 bacteria can't live in water heavily altered by volcanic ash

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as long as feathers are sandwiched between two layers of                 sediment

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the feathers preserve as a             corona or halo around the outside of the body

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based on fossil record, the following dinosaurs should probably be displayed with feathers

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definitely velociraptor since some skeletons have been found with fossilized feathers

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Tyrannosaurus should probably be as well

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we have no evidence that                           Tyrannosaurus had feathers

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we have evidence that some                   ancestors of Tyranosaurus had feathers

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therefore it's likely that the Tyrannosaurus kept these integumentary                       adaptations

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many dinosaur fossils preserve           scaly skin impressions

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there are many Hadrosaur fossils with skin impressions

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there are fossil from Stegasaurus which had scaly skin as well

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the skins of                         Ankylosaurus and Stegosaurus

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both have bones called osteoderms

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skin bones

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bones formed completely within the             dermis, the lower layer of skin

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some modern animals have osteoderms

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armadillos

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crocodiles

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some lizards such as the         gila monster

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            turtle shells are not osteoderms, as they form through a different process

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osteoderms are what give Ankylosaurs and Stegosaurus their spiky appearance

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Ankylosaurus

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form the knob of bone on the tail

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small and large             spikes

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Stegasaurus

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form the giant             plates on back and spikes on tail

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growing these extra exterior bones uses up a great deal of energy but they are very useful

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storing               calcium

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gathering heat from the sun

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protection from biting and clawing predators

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attract mates and intimidate rivals

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feather colors

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feather colors are not preserved in feather colors

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in modern birds, feather color is caused by the shape and arrangement of               pigment cells called eumelanosomes

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long and narrow correspond to black and gray

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short and wide correspond to brown and reddish           brown

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white feathers had no                           eumelanosomes

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narrow aligned in the same direction lead to glossiness

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some colors of some                   Theropods have been able to better determined by studying evidence of their eumelanosomes

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the Dromaeosaur Microraptor was probably glossy black

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the Archaeopteryx had at least some           black feathers

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we don't yet know of any fossil feathers that were blue,           green, or red

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Sinosauropteryx colors

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we can study preserved                       melanosomes to better determine colors

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red-brown with stripes most probable

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skin colors

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there is still no evidence regarding the color of dinosaur         skin